Acoustic radiation force impulse imaging of the liver: measurement of the normal mean values of the shearing wave velocity in a healthy liver.

AIM To find the normal mean values of the liver elasticity/stiffness by Acoustic Radiation Force Impulse (ARFI) Elastography in healthy subjects. MATERIAL AND METHOD This study was conducted on 137 healthy subjects without any known liver pathology or a history of jaundice by using the Siemens Acuson S2000TM Ultrasound machine with a convex probe . A routine ultrasound was also performed in each case, and the subjects with fatty liver changes or any other signs of a chronic liver pathology were excluded. In each subject, 10 measurements were taken and the median value of the 10 measurements was calculated, which was expressed in metres/sec (m/s). The inter quartile range method was used for the interpretation of the data. Only the measurements with an IQR of < 30% and a Success Rate (SR) of >60% were considered. The measurements were taken at 1-2 cm depth from the liver capsule through an intercostal approach, with the subject lying in the decubitus position. The mean ARFI values and the mean values according to the age and gender of the subjects were evaluated. RESULT Valid ARFI measurements were taken in 108/137 patients (78.83%). The mean value of the ARFI measurements in the normal individuals was 1.197±0.25 m/s. There were no significant differences between the mean ARFI values in men vs women (1.195±.25 vs. 1.199±0.26m/s, p = 0.939), and also among the different age groups (p>0.05). CONCLUSION In our study, the mean liver elasticity value (shearing wave velocity) which was obtained by ARFI in the healthy subjects was 1.197±0.25 m/s.